1000 MW燃煤锅炉深度调峰低负荷燃烧优化数值模拟  

Low load numerical simulation in combustion optimization of a 1000 MW coal-fired boiler at deep peak load regulation

作　　者：谷朋泰 蒋晓锋 GU Pengtai;JIANG Xiangfeng(Shanghai Power Equipment Research Institute Co.,Ltd.,Shanghai 200240,China)

机构地区：[1]上海发电设备成套设计研究院有限责任公司,上海200240

出　　处：《煤炭学报》2024年第S2期1154-1165,共12页Journal of China Coal Society

基　　金：国家电力投资集团统筹研发经费支持资助项目(KYB12022HB01)。

摘　　要：大型燃煤锅炉在响应深度调峰时往往涉及低负荷运行,需要克服炉膛燃烧稳定性降低、水动力安全性降低、选择性脱硝催化剂入口烟温降低等问题。其中,低负荷炉膛燃烧稳定性问题是电厂面临的最普遍的问题。低负荷工况下,炉膛主燃区温度降低、煤粉量和气流速度降低导致切圆燃烧稳定性变差,运行参数与方式选择不当可能引发炉膛熄火等较为严重的事故。针对低负荷炉膛燃烧稳定性降低的问题,在不涉及额外增加费用进行技改的前提下,对现有1000 MW塔式炉在20%低负荷运行时的运行参数与方式对炉膛燃烧的影响进行分析。在Fluent中建立了耦合炉膛燃烧与水冷壁工质传热的数值模拟模型,通过UDF将炉膛燃烧热负荷传递至水冷壁,计算水冷壁工质参数时考虑单相及两相流动的不同特性,以及两相流动过程中产生的传热恶化现象,再将水冷壁工质侧的计算结果反馈至炉膛燃烧侧进行计算,循环迭代至偏差满足要求。克服了已有文献通常在壁面换热计算时对计算过程与边界条件进行简化处理导致计算精度降低的问题。从烟气温度随炉膛高度变化、切圆组织、煤粉喷口轴线方向着火情况、氮氧化物排放等角度,分析一次风速、投运磨煤机组合、二次风配风方式等关键因素对稳燃能力的影响。结果表明,改变二次风配风方式对炉膛燃烧影响最大,改变一次风速次之,改变投运磨煤机组合影响相对最小。采用正塔配风相对于采用倒塔配风,可提高煤粉喷口截面温度174 K,但对应的氮氧化物质量浓度从343.9 mg/m^(3)增加至382.5 mg/m^(3)。当正塔配风时,主燃区下部氧量充足,燃烧剧烈,形成较强的氧化性气氛,在主燃区形成范围较大的冠状高温区域,燃烧切圆自外向内的温度降低趋势减弱,且煤粉引燃情况所受影响较小。计算结果可为大型燃煤锅炉深度调峰低负荷运行燃烧优�Low load operation is usually involved during response for deep peak load regulation for large-scale coal-fired boilers,which requires overcoming problems such as the lowering of boiler combustion stability,hydrodynamic safety,and flue gas inlet temperature of SCR denitrification,while low load boiler combustion stability is the most common problem faced by the power plants amongst the aforementioned problems.During low load working condition,temperature of main combustion region decreases,amounts of coal and airflow velocity decrease as well,causing the worsening of tangential combustion stability.The improper configuration of operating parameters and regimes may lead to serious accidents such as furnace flameout.For the problem of lowering boiler combustion instability during low load,under the prerequisite of no additional fee for technical overhaul,the impact of operation parameters and regimes on furnace combustion during 20% low working load of a 1000 MW tower-type boiler is analyzed.A coupled numerical simulation model of furnace combustion and working medium heat transfer in water wall is established in Fluent.Heat load is transferred to water wall by UDF.Different characteristics of water wall working medium in single-phase flow and two-phase flow,as well as heat transfer deterioration in two-phase flow,are taken into consideration,which are subsequently transferred to furnace combustion side for further computation.Iteration is carried out until deviation meets requirement.The problem of lowered computational accuracy caused by simplifying computation procedure and boundary condition for heat transfer of surfaces is resolved.The impact of key factors such as primary air velocity,mill combination,and secondary air distribution on combustion stability is analyzed from the prospective of flue gas temperature along furnace height,tangential combustion configuration,ignition condition along axial direction of coal nozzle,and NO_(x) discharge.According to the results,secondary air distribution has the most si

关 键 词：深度调峰 燃烧优化 一次风速 配风方式 

分 类 号：TK16[动力工程及工程热物理—热能工程]